THE MOLECULAR BASIS OF INHERITANCE
GENE MUTATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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a silent mutation, which codes for the same amino acid.
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a missense mutation, which codes for a different amino acid.
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a nonsense mutation, which codes for a premature stop.
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Detailed explanation-1: -1). Because an insertion or deletion results in a frame-shift that changes the reading of subsequent codons and, therefore, alters the entire amino acid sequence that follows the mutation, insertions and deletions are usually more harmful than a substitution in which only a single amino acid is altered.
Detailed explanation-2: -If the substitution leads to an amino acid with very different structure and properties the mutation is nonconservative and will probably be deleterious (bad) for the resultant proteins structure / function (i.e. the sickle cell point mutation).
Detailed explanation-3: -Frameshift mutation yields truncated, dysfunctional product proteins, leading to loss-of-function, genetic disorders or even death. Frameshift mutations have been considered as mostly harmful and of little importance for the molecular evolution of proteins.
Detailed explanation-4: -’Nonsense’ mutations are particularly problematic: they are associated with many genetically inherited diseases, such as the blood disorder -thalassaemia, and are common in cancer (Bhuvanagiri et al., 2010).